If two or more RF technologies operate in the same device and share common frequency band, it is not possible to transmit/receive simultaneously in the same device.
A problem arises if the circuitry for a first technology is performing a procedure that requires communication but does not have use of an antenna. It is likely that the procedure will be corrupted or take a long time to complete.
As an example, without loss of generality, on the current implementation of HCl and Link Manager Protocol in Bluetooth, when an audio link is established adaptive frequency hopping (AFH) is enabled and local channel assessment is done by both Master and Slave devices. The Master and Slave each create a local channel classification report. The Slave report is provided to the Master which uses the classification reports to update the AFH channel map.
The AFH channel map is then sent to the Slave and used by both Master and Slave to define the channels they will both use.
If the Master (or Slave) shares an antenna with other transceiver circuitry such as WLAN circuitry, it is not possible for the Bluetooth circuitry and the WLAN circuitry to share the antenna simultaneously. Use of the antenna is therefore granted to only one of the Bluetooth circuitry and the WLAN circuitry at a time.
A problem arises if the Bluetooth circuitry is performing the AFH procedure but does not have use of the antenna. It is likely that the classification report created will be corrupt. This may result in an inaccurate AFH channel map and therefore greater interference in the Bluetooth connection resulting in lower audio quality.
A similar problem arises whenever two unsynchronized processes compete for use of a resource and a first process uses the resource on an on-going basis, but such use is not taken account or given low weight in the arbitration decision that determines which of the processes should use the resource. The result produced by the first process may be corrupted if the first process continues without use of the resource or the data rate is reduced.